#!/usr/bin/env tclsh

proc seat {s} {
  set fb [string range $s 0 6]
  set lr [string range $s 7 9]

  set min 0; set max 127
  foreach c [split $fb {}] {
    switch -- $c {
      F {
        # Keep the lower half.
	set width [expr {$max - $min + 1}]
	set max [expr {$min + $width/2}]
      }
      B {
        # Keep the upper half.
	set width [expr {$max - $min + 1}]
	set min [expr {$min + $width/2}]
      }
    }
  }
  set fb $min

  set min 0; set max 7
  foreach c [split $lr {}] {
    switch -- $c {
      L {
        # Keep the lower half.
	set width [expr {$max - $min + 1}]
	set max [expr {$min + $width/2}]
      }
      R {
        # Keep the upper half.
	set width [expr {$max - $min + 1}]
	set min [expr {$min + $width/2}]
      }
    }
  }
  set lr $min

  expr {$lr + $fb * 8}
}

while {[gets stdin line] >= 0} {
  if {$line eq ""} continue
  set seats([seat $line]) 1
}
for {set i 0} {$i < 1024} {incr i} {
  if {! [info exists seats($i)]} {puts $i}
}